The present invention is a new chemical process for making cyclic dicarboxylic acid imides and thereby the corresponding diacids. More specifically the invention relates to a process for making substituted cyclic imides of oxydiacetic acid and N-substituted iminodiacetic acid by a dehydrogenation process.
It is known that p-dioxanone is formed when the vapors of diethylene glycol are passed over a copper dehydrogenation catalyst such as copper chromite. This process is described by H. R. Guest et al. in U.S. Pat. No. 2,900,395. It is also known that an N-alkyldiethanolamine is dehydrogenated to the N-alkyl-2-morpholinone by an analogous process as described by Schultz et al., U.S. Pat. No. 3,073,822 and by Cenker, U.S. Pat. No. 3,324,123. The present process represents a step beyond these disclosures of the prior art.